The present invention relates to an elastic polyurethane fiber.
Elastic polyurethane fibers are generally produced by wet spinning, dry spinning or melt spinning.
Polyurethane fibers produced from polyether diol have been known to be elastic fibers, but they are inferior in resistances to chlorine, light and heat.
Elastic fibers comprising polyurethanes produced from polyester diol are inferior in resistances to water and mildew.
Japanese Patent Application Laid-open No. 101496/1973 discloses a polyurethane utilizing 3-methyl-1,5-pentanediol and suggests that the polyurethane can be melt spun.
Japanese Patent Application Laid-open No. 173117/1985 describes elastic fibers made of polyurethanes utilizing polyester diols from hexamethylene glycol and 1,10-decanediol. However, the use of these long-chain, non-branched diols cannot give fibers with excellent elastic recovery, low temperature resistance and elongation.
Japanese Patent Application Laid-open No. 713/1972 discloses an elastic fiber made of a polyurethane utilizing a polyester diol comprising 2,4,4-trimethylhexanediol and adipic acid; U.S. Pat. No. 3,097,192 one prepared from a polyurethane derived from a polyester diol utilizing 2,5 -hexanediol or 2,2-dimethyl-1,3-propanediol; and Japanese Patent Application Laid-open No. 97617/1988 one comprising a polyurethane utilizing (2,2-dimethyl-1,3-propane dodecane-dioate) glycol. However, these polyester diols, which are derived from diols having at least 2 methyl groups cannot give polyurethanes which form fibers with high heat resistance, elastic recovery and resistance to low temperatures.
In view of the foregoing, the present invention provides elastic polyurethane fibers being excellent in all of the properties of resistances to chlorine, water and mildew, elastic recovery, resistances to heat and hot water, and having high elongation.
While a polyurethane derived from high polymer diol utilizing as starting materials a long-chain diol and dicarboxylic acid can give fibers having improved resistances to hydrolysis and mildew and other properties, the fibers are significantly poor in elastic recovery, resistance to low temperatures and elongation. For example, elastic polyurethane fibers comprising a polyurethane utilizing polyester diol obtained by copolymerizing adipic acid, azelaic acid, sebacic acid, 1,10-decanedicarboxylic acid or the like with a linear diol, such as 1,4-butanediol, 1,6-hexane glycol, are extremely inferior in elastic recovery, resistance to low temperatures and elongation. Where propylene glycol or neopentyl glycol is used as the diol component to improve the above properties, the resultant elastic polyurethane fibers are poor in resistances to heat, hydrolysis and hot water. In the elastic fibers obtained from the polyurethane having the composition of the present invention, all of the above inconsistent problems are solved, and the fibers are excellent in resistances to hydrolysis, mildew, heat and low temperatures, as well as in elastic recovery and elongation, and further have high retention of the properties after they have been treated with hot water at 130.degree. C. for 90 minutes.